Technical Field
The present disclosure relates to a terminal that can be connected to a conductor portion of a coated conductive wire, a crimp terminal, a wire harness, and a method for manufacturing the crimp terminal.
Background
In the field of electric devices, coated conductive wires such as wire harnesses are usually used. A connecting terminal is fixed to the conductor portion of such coated conductive wire for joining to another connector. In order to adequately suppress the corrosion of the conductor portion and maintain stable electric conduction, it is important to prevent ingress of moisture to the conductor portion. Since the connecting terminals used in vehicles may be exposed to moisture when the vehicles are driven in rainy weather or washed and also due to condensation, it is even more important to prevent ingress of moisture to the conductor portions of such connecting terminals. Further, aluminum electric wires using aluminum for the conductor portion have recently attracted attention as a means for improving fuel efficiency by reducing the weight of vehicles. However, where such aluminum electric wires are used together with connecting terminals formed from a dissimilar metal, a so-called electrolytic corrosion can occur in the connecting portion of the conductor portion and the connecting terminal due to the presence of water or moisture.
Accordingly, a connecting structure has been suggested in which a connecting portion is sealed with an insulator in a state in which the conductor portion of a coated conductive wire is connected to a connecting terminal in order to prevent ingress of moisture to the conductor portion (see, for example, Japanese Laid-Open Patent Publication No. 2011-233328).
In the abovementioned related art, since the cost required for sealing with an insulator is relatively high, there is still room for improvement. A different configuration can be also considered in which a crimp portion capable of accommodating and crimping the conductor portion of a coated conductive wire is formed by bending a plate material, and the conductor portion is surrounded thereby.
A technique to be used with such a configuration has been suggested in which a terminal having a hollow (tubular) crimp portion closed at one end is used, an end portion of an electric wire is inserted into the crimp portion, and the crimp portion is then crimped by swaging to protect the end portion of a core wire from adhesion of rainwater or seawater (see, for example, Japanese Laid-Open Patent Publication No. 2006-331931 and Japanese Laid-Open Patent Publication No. 2001-250602).
The inventors have also suggested a technique relating to a crimp terminal ST which is a terminal having a hollow (tubular) crimp portion closed at one end, the terminal being obtained, as shown in FIG. 13, by forming a tubular crimp portion Ta and a box-shaped connector portion Tb by punching and bending a plate strip material and then forming a transition portion Td by squeezing the connecting portion of the crimp portion Ta and the connector portion Tb.
In such a crimp terminal ST, a sealed structure is formed by laser welding a butted interface Tc and a lapped portion Td, which appear in the portion bent into a hollow shape, in the crimp portion Ta and the transition portion Td. More specifically, firstly, the butted interface Tc formed along the axial direction is laser welded in the upper end portion of the crimp portion Ta that has been bent into a cylindrical shape in the crimp terminal ST. Then, the transition portion Td is formed, and the lapped portion Te of the transition portion Td is also laser welded and sealed in order to suppress the ingress of water to the conductor portion.
In the above-described related art, laser welding is performed on the lapped portion Te at which plate materials are closely attached to each other by squeezing the transition portion Td. Since the laser welding is performed along a straight line in the terminal width direction, the strength of the transition portion Td can be thereby decreased. That is, the welding line may become a break line and the transition portion Td may break along the trajectory of laser welding in the transition portion Td.
The present disclosure is related to providing a terminal, a crimp terminal, a wire harness, and a method for manufacturing the crimp terminal such that ingress of moisture to the conductor portion of a coated conductive wire is adequately suppressed while preventing local decrease in strength and deformation.